Thin Film Transistor-Liquid Crystal Display (TFT-LCD) has the advantages of low weight, low power consumption, less radiation and the like. In nowadays life, TFT-LCD has gradually replaced the dominant position of the traditional Cathode Ray Tube (CRT) in the field of display. The basic principle for liquid crystal to display is that: because liquid crystal molecules in different arrangement states have different polarization effect with respect to the light, the transmissivity of light can be controlled via the liquid crystal molecule in different arrangement states, and different gray levels of red, blue and green lights can be generated through liquid crystal molecule's such property, making LCD generate rich image.
With the development of TFT-LCD driving technology, users' requirements for picture quality are increasing, where color accuracy is one of important parameters to evaluate picture quality. The present research reveals that color shifting phenomenon is a common problem that affects the color accuracy of TFT-LCD picture. The main reason for causing color shifting phenomenon is that liquid crystal molecule has a different transmission property with respect to red, green and blue lights, and if the lights of these three colors use the same Gamma voltage, although the resulting synthesized gray level satisfies the target Gamma curve, Gamma curve for these three colors do not coincident with each other, and that is so-called color shifting phenomenon. FIG. 6 is a schematic diagram for illustrating generation of color shifting according to the prior art, where ordinate represents transmissivity, and abscissa represents gray level. As can be seen from FIG. 6, when using the same kind of Gamma voltage, for the same gray level, the respective transmissions for red light 11, blue light 12 and green light 13 are different from ideal values. When color shifting phenomenon is severe, the phenomenon that the picture is a little blue or red often occurs, degrading the picture quality greatly.
Prior art provides many solutions for such problem. One solution is Accurate Color Capture (ACC) solution, in which the levels for red, green and blue lights are adjusted so that the Gamma curves for these three colors are approximately identical. This solution mitigates the color shifting phenomenon to some extent, however, its adjusting accuracy is not high. Moreover, it requires to add new functional module in timing controller, thus increasing the complexity of manufacture process and also increasing the manufacture cost. Another solution uses three resistor-chains to adjust those three colors respectively. FIG. 7 is a structural diagram of the solution for employing three resistor-chains according to the prior art. This solution comprises three resistor-chains, that is, a first resistor chain 21, a second resistor chain 22, and a third resistor chain 23, each resistor-chain corresponds to the output of pixel driving voltage for one color. However, this solution needs to establish three resistor-chains inside the source driving IC. This not only makes design complex, but also increases the cost greatly.